I am looking for a word ...

Fair to middling ?

Are you content?

Surviving

Middling?

I use an expression from the North East = 'Nae sae bad', which I feel is marginally glass half full rather than half empty.

My late grandmother used to intimidate the nursing staff at her home by saying 'It would be wrong to day I'm happy but I'm content!'

Say not day!

I remember a friend saying that she upset a bride by writing on the card she sent to them 'I hope you will always be content'

The bride wanted to know why she hadn't wished them 'happiness' and my friend said that contentment could last a lifetime but that happiness could be fleeting.

I am content with my lot, but worry can get in the way
I think fair to middling probably is where I am at the moment

I just feel we should have a word in the English language that sums up the bit between unhappy and happy.

Jalima your friend was right.
Happiness can last a short time maybe even just a few minutes or longer if your lucky, but it can also disappear in a flash.

Do any G/N linguists know if there is a word in another language that would fill the blank between unhappy and happy?

Granny23 my scots GP would say
'Aye I'm no so bad, how's yer sel?'
Not so far from what you said.

Maybe if you are Unhappy then you must be happy

Average?

I'd go for 'normal'

Are you perhaps overthinking this, Cherry?
If in answer to the question 'How are you?' I were to say 'I'm fine, thank you' I would mean that I was ok, not bursting with happiness but not unhappy either.
I certainly wouldn't be worrying that I couldn't find the right word to describe my state of mind.

I think that "fair to middling" is perfect. Agreed it is not one word but you can't have everything in life. At least with "fair to middling" it leaves it open to the recipient to enquire further or not as they choose.

I agree with fine. Short and sweet. Not overly exuberant or ecstatically joyful but I think it succinctly encapsulates fair to middling very well, but more briefly.
Don't like the "I'm good" thing. I think other languages do have phrases that translate along the lines of "things are going well", but in fewer words.

Equable?

7 / 10 !!

How about 'at ease' ?

"Can't complain" or "Could be worse".

Different s...t, same day!

"Canny"

Canny means something different up here!

I think OK is the word actually

Dunno how you are Cherrytree but I'm hunkytiddlydory-ish.

Muddling along.